Rotational Components of Seismic Motion Based on Surface Wave

In this paper, the appropriate methods are presented to obtain the seismic rotational components caused by the arrival of the surface waves applying the theory of elastic wave propagation. The rocking component around a horizontal axis and the torsional component around a vertical axis are generated respectively by the Rayleigh and Love waves. At the same time, the calculation formulations of phase velocities about these waves with frequent dispersion are derived and introduced to the rotational components, which may be more suitable for engineering practice. A procedure is developed to compute the time histories. Finally, numerical results have shown that the rotational motions have more energy than the translatonal motions in high frequent range by using the given methods.